<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>组合式API</title>
</head>
<body>
  <div id="app">
    {{ count }}
    <button @click="add">加1</button>
  </div>
</body>
<script src="../lib/vue.global.js"></script>
<script>


  const { ref, onMounted, onUpdated } = Vue
  function useCount () {
    const count = ref(0)

    const add = () => {
      count.value = count.value + 1
    }

    return {
      count, add
    }
  }


  function useTitle (count) {
    onMounted(() => {
      document.title = `点击了${count.value}次`
    })

    onUpdated(() => {
      document.title = `点击了${count.value}次`
    })
  }
  Vue.createApp({
    setup () { 

      const { count, add } = useCount()
      
      useTitle(count)
      
      return { 
        count,
        add
      }
    }
  }).mount('#app')
</script>
</html>